Cannulas or other puncture devices are normally inserted into the vein or artery of the arms and legs with direct visualisation of the position of the vein or artery. The demand for sterility is small and thus, the skin is typically just washed or disinfected before the puncture. The puncture device is to be maintained in position after insertion. Therefore, a film is attached to the skin of the patient, close to the puncture site. The film often comprises an open-ended slit or a slot enabling the film to be arranged around the puncture device. Hereby, the puncture device is maintained in the anatomical structure.
The puncture site can be optimized and the target visualised using ultrasound. Hereby, the target is precisely localised and the puncture device can be inserted optimally into the anatomical structure such as a vein or an artery.
The advantage of using ultrasound for insertion of needles or other puncture devices into an anatomical structure of a patient is illustrated for example by the statement of the National Institute for Clinical Excellence (NICE) on the use of ultrasound locating devices for placing central venous catheters (Technology Appraisal Guidance No. 49, September 2002) by stating that “Two-dimensional imaging ultrasound guidance is recommended as the preferred method for insertion of central venous catheters into the internal jugular vein in adults and children in elective situations.” A recently published study concludes that implementation of the NICE guidelines significantly reduces the number of complications observed during or after the insertion (Wigmore T J et al., Br J. Anaesth. 2007 November; 99(5): 662-5).
The position of the exact puncture site can be marked and the ultrasonic device removed before the puncture. However, minor movements of the patient often change the location for the exact procedure site. Thus, the use of real-time visualisation during the entire procedure is advantageous.
Ultrasonic gel or similar contact means is needed to obtain a proper ultrasonic image. Applying ultrasonic gel to the skin of the patient, however, makes proper attachment of the film to the skin difficult after the insertion of the puncture device. Thus, the maintaining of the puncture device in a correct position is also impaired. Hereby, the puncture device may be displaced, detached or damage the anatomical structure. Furthermore, the non-sterile ultrasonic gel may pass the skin barrier and hereby contaminate the puncture site.